Project Summary/Abstract The primary goal of this proposal is to establish and apply an in vitro human podocyte model of APOL1 associated podocytes using podocytes derived from human induced pluripotent stem cells (iPSCs). The research will combine stem cell biology, CRISPR-mediated gene targeting, genomic and epigenomic techniques. The main focus of the application is APOL1 associated kidney disease (AAKD), including focal segmental glomerulosclerosis (FSGS), HIV associated nephropathy (HIVAN), and hypertension-attributed end stage kidney disease (H-ESKD). High risk (HR) APOL1 genotypes (having 2 risk alleles of renal risk variant APOL1) account much of the excess risk of FSGS, HIVAN, and H-ESKD among African Americans. 12-15% of African Americans are carriers of HR APOL1. Estimated 15-20% of these HR APOL1 carriers will develop AAKD in their lifetime. There are no functional screening tools to identify these 15-20% ahead of time. Podocyte injury/loss (podocytopathy) is a common denominator of AAKD. The mechanism by which renal risk variants APOL1 cause podocytopathy is unknown. Natural lack of APOL1 gene in experimental animals limits utility of animal models. Lack of access to relevant human podocyte has hindered research progress. The iPSC-podocyte model of AAKD leverages advantages of stem cell approaches, namely ability to generate mature podocytes that captures complexity of human genetics and epigenetics. This approach overcomes the previous problem of lack of access to human podocyte. We will apply this iPSC-Podocyte model to discover podocyte determinants of AAKD and mechanism of APOL1-induced podocytopathy. iPSC-podocyte will be utilized to screen drug library as well as perform genome-scale Cas9 mediated knockout screen. Application of this human iPSC-podocyte model of AAKD as proposed in this application is likely to yield disease biomarkers that will be useful for population-wide screening as well as unveil mechanistic insights and therapeutic candidates.